Fig. 11-3. Variation of apparent resistivity with ratio of electrode spacing and 



hole diameter for two resistivity ratios — -— (after Hummel). The 



drilling mud (p) 



electrode interval CPi is as shown in Fig. 11-ld. 



100 



70 



60 



%Oil 

 % Saltwater 



Fig. 11-4. Variation of formation resistivity with oil and water content (after 

 Martin, Murray, and Gillingham). (I, porosity 45 per cent; II, porosity 20 per 

 cent; resistivity in ohm-meter.) 



830 



